Automatic-releasing thread-cutting tool



Nov. 1, 1938. A. F. BRElTENsTElN AUTOMATIC RELEASING THREAD CUTTING TOL 5 Sheets-#Sheet 1 Filed Aug. 25, 1957 n u ll z j m J V A 53,

.ad a Si 5 Sheets-sheet 2 Nov. 1, 193s.

A. F. BRElTENSTElN AUTOMATIC RELEASING THREAD CUTTNG TOOL Filed Aug. 25, 1937 )MFM Patented Nov. 1, 1938 urNi'r se Sfmt PATENT @FFME AUTOMATIC-RELE-ASIN-GS THREAD-GUT- TING TOOL Albert F; Breitenstein; New- Haven, Conn., as-

signor to The Geometric ToolE Company; New Haven, Conn., a-corporationrof Connecticut Application. August 25,-y

8 Claims.-

This invention relatesl to anrimprovement in. automatic-releasing thread-cuttingtools,4 that` is to say, thread-cutting toolswhich automatically retire their threadrcutting. chasers from engagement with the work-,to thus permit the ready and rapid axial separation ofi` the work and tool.

More particularly, the present inventionrelatesl to thread-cutting tools of the character referred.

to, which are employed for cutting pipe-threads mv andother similarly-tapered Ythreads,` and which rely upon normally-stationary thread-cutting chasers which have their series of thread-cutting teeth arrangedat the desired angle in contradistinction to thread-cutting toolsAk whichv proy gressively retire their chasers during vthe normal thread-cutting operation, in order to effect the.

desired taper'.

Thread-cuttingtools ofthe type to `which the present invention relates are. apt to leaveone or 0. more objectionable longitudinal shoulders upon the threaded portion of' the work (especially upon resilient material such assoft brass) after the tapered chasers have.` been retired. radially from the work, much in the manner illustrated in: Figs. 13 and .14 of the accompanyingdrawings. The problem oi overcoming the diculty just referredto has. longY vexed: thoser skilled inthe art.

The main'object, therefore, of thepresent in.-V

ventionis to provideza superior automatic-'releasing thread-cutting tool of the type referredto;

which will produceA tapered'threads free from abruptlongitudinal shoulders.

A further object of the present invention is'- to provide a superiorautomatic-releasing threadcutting tool whichwill maintain its-threadfcutting chasers in rixed'radialV position during the normal threading operation, and which will at the termination of` such operation retire the a View* thereof in central longitudinal 555'section takenfon. the liner-'3,-3fof Fig.;2, theparts.

1937, Seriali-No. 160,749?

being shown inithepositions-which they assume fon a normal-vthread-cutting` operation;

Fig. LLisa sectional viewfcorresponding'to Fig.'

3; butl less comprehensivethan the same, and showing theparts in-the positionswhich they assume; after they completeY retirement of.- the chasers;

Fig. 5 is a fragmentary sectional'view on an enlarged scale showingisome of the parts of the mechanismillustrated in-vthe upper portion of Fig. 3;

Fig. 6 is ali-fragmentarysectional view correspondingato Fig.` 5;.but showing theiparts'- infthe positionswhich they. assume at the instant the latch-member has been shifted.` sufficientlyv to .l

start they brief progressive retirement of the chasers;V f

Fig.. 7 is a fragmentary sectionalview taken onthe-line 1-1 of Fig. 2;

Fig;4 8;,is. asimilar viewtaken ontheY line -8---8` of. Fig. 2;

Fig.l 9 isa transversefsectional View taken ony the line 9--9ry of Fig.- 3;

Fig. 10.is a perspective viewfof thelatch-member ofthe structure of Figs.' l to 9 inclusive;

Fig. l1Y is a viewy in side elevation of anfautomatic v collapsing tap' embodying. the present invention;

Fig. 12 isa view thereof in central `longitudinal section;

Fig. 13- Ais-a schematic sectional view showingA the action of one`of lthe chasers .of .the self-opening die-headfin cutting tapered threadsupon the work and the resultant longitudinal shoulder upon-the latter;

Fig. .14 isa broken.- face View ofv a section of the work shownffin Fig.l 13;

Fig. 15 is a-transverse sectional View through thefwork, `showing the erasure vof. the longitudinal shoulder appearing in Fig'. 13, bythe novel action'r of the self-opening dieehead structure ofFigs. 1`

to 10 inclusive;VV

Fig.-- 16'is fa.; fragmentary'perspective View of the Chaser-operating"sleeve; and` Eig.' 1'7 isian enlarged fragmentary View of the let-oli. shoulder.v ande. cooperatingl parts of the structure showninr Fig. 12';

Thev automatic-releasing or self-'opening diehead. herein-chosen for the illustration ofthe presentinventionf in Figs.. lv toy l0-inclusive comprises a= body-member, generally designatedby the referenceA character 2li.,` having atfits forward endanenlargedheadportion 2 Iland provided at its .rearend withz.azh'ol1ow shank 22'.Y The. said' headeportion 2 I .risformed in' its` forward face with The inner edge of each of the chasers 24, just referred to, is formed with a series of threadcutting teeth 25 tapering forwardly and out-V wardly at an angle substantially corresponding to the desired angle of the threads to be cut upon the work. For purposes of clarity of illustration, the taper of each series of thread-cutting teeth 25, just referred to, has been exaggerated over and above the taper customary in pipe-threads.

The chasers 24 are retained in place'in the slots 23 in the head-portion 2| of the body-member 2D by means of segmental plates 26 which are secured to the said head-portion` by screws 2l. Each Chaser is formed at its outerend with a sloping cam-surface 28 which is engaged by a similarly-sloping cam-surface 29, one of which latter is formed upon the inner forward corner of a Ysubstantially-cup-shaped Chaser-operating sleeve 30`adjacent each of the said chasers. I'he said Chaser-operating sleeve is mounted upon the body-member 20 with capacity for axial sliding movement thereon, and bears at its forward end upon the periphery of the head-portion 2| of the body-member, and at its rear end bears upon the periphery of a latch-carrying ring 3| mounted upon the said body-member with capacity for axial adjustment thereon. The axial adjustment of the latch-carrying ring 3|, just referred to, is effected by an adjusting-nut 32 threaded upon the body-member 20 just forwardly of the shank 22 thereof.

The latch-carrying ring 3|, above referred to, is formed with a transverse notch 33 provided for the reception and guidance of a substantiallysemicircular latch-member 34, the outer periphery of which corresponds in curvature to the curvature of the outer periphery of the latchcarrying ring 3|, above referred to. The forward face of the latch-member 34 constitutes a latching-abutment Vgenerally designated by the refer- ,ence character 35 and is adapted tovengage with a substantially-semicircular latching-abutment 36 curved lengthwise of itself and formed in the interior of the Chaser-operating sleeve 30 for the purpose of releasably holding the said sleeve in its forward chaser-closing position against the rearward urge of a pair of retracting-springs 31-31 (Figs. 8 and 9). The said retractingsprings are respectively located at diametricallyopposite points in the die-head structure, as Vshown in Fig. 9, and have theirrforward ends seated in sockets 38 opening rearwardly through the head-portion 2| of lthe body-member 20. The rear end of each of the said retractingsprings is seated in a socket 39 opening forwardly from the adjacent contracted portion of the Chaser-operating sleeve 3B.

To pro-vide for the erasure of longitudinal shoulders which might otherwise be left upon the work by the chasers, the outer forward corner of the latch-member 34 is cut away to provide an outwardly-and-rearwardly-inclined let-off shoulder 35a which extends from a radially-extending latching-shoulder 35h of the said latchmember 34 to the outer periphery thereof. The said let-oli shoulder is.most clearly shown in Figs. 5, 6 and 10 of the accompanying drawings and, together with the latching-shoulder 35h, constitutes part of the latching-abutment 35. In the particular type of structure shown in the said gures, the let-olf shoulder 35a preferably has an inclination of about 81/2" with respect toI the plane of the latching-shoulder 351)I of the latchmember 34, but in any event, the said let-off shoulder must have a non-camming angle-relationship of substantially less than 45"l with respect to the plane of the latching-shoulder which it intersects, so that the said let-off shoulder Chaser-operating sleeve 30, by means of an external abutment to permit the rearward retirement of the said sleeve under the urge of its springs 31-31, a tripping-sleeve 4| is employed which is' mounted upon the Chaser-operating sleeve 30 with capacity for axial movement thereon. The said tripping-sleeve 4| is provided with an internal cam-surface 42 which, when the sleeve is moved rearwardly, is adapted to exert inward pressure upon a ball 43 which is movable radially in a radial guide-passage 44 formed in the rear portion of the Chaser-operating sleeve 3|). The said ball 43 is adapted to bear upon the periphery of the latch-member 34 for the purpose of urging the latter inwardly, as will hereinafter appear.

Save for the let-off shoulder 35a, in particular, the die-head organization above described may be said to be old in the art and it has been set forth and described herein for the purpose of enabling the operation of the let-o shoulder or its equivalent to be properly understood.

For'purposes of description, Vlet it be presumed that the die-head structure is mounted by means of its shank 22 in the rotating chuck of a threadcutting machine and that it is advanced axially toward the work 45 for the purpose of cutting a pipe-thread thereon.

After the die-head has been threaded onto the work as above described to the desired extent, the tripping-sleeve 4| will have been arrested, by any suitable stop, against further forward movement with thedie-head structure so as to cause its cam-surface 42 to act through the ball 43 to move the latch-member 34 inwardly into the position in which it is shown in Fig. 6, thus bringing the sloping let-off shoulder 35a of the said latch-member into position for coaction with the lower edge of the latching-abutment 36 in the Chaser-operating sleeve 3i). The chasers 24 will now be in progress of cutting the threads upon the work 45 and each will be producing a longitudinalshoulder 46 (Figs. 13 and 14) upon the threaded portion of the work 45. If at this time the chasers were tobe instantly released from the work, as is the ordinary practice, the shoulders` 46 or their equivalent would remain visible upon the threaded portion of the work 45. Instead, however, of abruptly retiring the chasers out of engagement with the work, the let-01T shoulder 35a upon the latch-member 34 will now come into action and, though operating within a very Vshort period of time, will now cause the said chasers to retire slowly for a short distance to thus erase, so to speak, the longitudinal shoulders 46 from the threaded portion of the work, as may be seen by comparing Fig. 13

with Fig. 15 of the accompanying drawings. As soon as-the outer edge of the let-olf shoulder 35a. clears the inner edge ofthe latching-abutment 35, the Chaser-operating sleeve-30 will be snapped rearwardly by its retracting-springs 31 into the position in which it is shown in Fig. 4, thereby permitting the individual retracting-springs 41 of the chasers 213 to force the said chasers radially outwardly completely clear of thework so that the die-head structure andthe work may be` axially separated preparatory to another threading operation.

In Figs. 11 and 12 is shown a so-called collapsing tap structure incorporating the novel let-off feature of the present invention. The c ollapsing tap referred to includes a cylindrical body-member 5|) having an axial bore 5| for the reception of a Chaser-operating plunger 52 which reciprocates therein. The forward end of the said VChaser-operating plunger is tapered and formed with Chaser-actuating ribs 53 tting into corresponding grooves in the inner ends of a set of thread-cutting chasers' 54, each ofY whichis formed in its outer edge with a slopingseries of thread-cutting teeth 55. The chasers 54 are mounted in radial grooves 55 formed in the forward end of the body member 5&1 and are normally held in place against forward displacement by a cap 51 secured to the forward end of the said body-member 55.

Mounted upon the forward portion of the bodymember 55,;with capacity for axial sliding movement thereon, is a latch-carrying sleeve 58 which in turn has mounted upon it, also with capacity for axial movement, atripping-sleeve 59. The rear portion of the tripping-sleeve 59 bears upon the periphery of an annular ange B which forwardly projects from an adjusting-ring 5|, which latter is provided with internal threads 52 for engagement with external threads 63 formed upon the periphery of the body-member 59.

Adjacent its rear end, the Chaser-operating plunger 52 is formed with an elongated diametrical passage 64 through which extends a coupling-v bar 55 which extends through a clearance-slot BB formed in the adjacent portion of the bodymember 5B and into coupled relationship with the latch-carrying sleeve 58, before described. The said coupling-bar 65 thus serves to couple the latch-carrying sleeve 58 with the chaseroperating plunger 52 for concurrent axial movement with respect to the collapsing-tap structure.

Projecting rearwardly from the chaser-operating plunger 52 is a bolt 61 having at its rear` end a kerfed head 68, the under face of which latter forms a forwardly-facing spring-seat for engagement by the forward end of a helical retracting-spring 69 which encircles the rear portion of the bolt 61 and bears at its forward end against a washer-like spring-seat 1|! through which the said bolt 61 extends, as is clearly shown in Fig. 12.

The latch-carrying sleeve 58 is formed with a notch 1| which receives and guides a radiallymovable semicircular ring-shaped latch-member 12, the rear face of which constitutes a latchingabutment similar to the latching-abutment 35 of the self-opening die-head before described, and which is adapted to engage with a latching- Vabutment 14 constituting the forward face of the flange 55 of the adjusting-ring 5|, before described. Idke the latching-abutment 35 of the latching-member 34, before described, the latching-abutment formed by the rear face of. the

latching-member 12-V now under discussion,` is formed with a radially-extending latching-shoulder 15a and a sloping let-off shoulder 15b which joins the; latching-shoulder 15a, with the outer surface of the latch-member 12. To effect the inward movement of the latch-member 12 to permit the inward` retirement of the chasers 54,`

thesaid latch-member is formed in its forward outer corner with a cam-surface 16 which is engaged by a `similarly-sloped cam-surface 11 formed in the interior of the tripping-sleeve 58.

`For the purpose of manually moving the tripping-sleeve 59 rearwardly to effect the manual tripping ofthe `tap or for moving the said tripping-sleeve forwardly, to cause the same in turn to similarlymove the'latch-carrying sleeve 58, to reset the chasers 54 in. their projected or operative positions, a lever-handle 18 is employed. The saidlever-handle is mounted in the trippingsleeve 59 upon a transverse pin 19, which latter extendsdiametrically through a sphericallycontoured boss on the said handle. The said spherically-contoured boss 80 ts within a passage 8|; in the `said sleeve 59 and serves to exclude chips .and dirt from the interior of the diehead` structure. VThe inner end of the leverhandle 'I8 projects inwardly through a clearancepassage 82 formedV in the latch-carrying sleeve 5B and is provided with a spherically-contoured terminal` 83 fitting into a socket 84 formed in the body-member 50, before referred to.

Inlorief,A the operation of the collapsing tap illustrated'in` Figs. 11 and 12 is as follows:

Assuming that the parts are in the positions inV which they are shown in the drawings, the tap will be moved toward the work or the work towardthe tap so as to cause the now-projected chasers 54` to enter the work. vWhen the work has been threaded to `the desired extent, the tap may be tripped for retiring the chasers 54 in- .if

wardly completelyout of engagement with the work either by an abutment acting to move the tripping-sleeve 5S rearwardly with respect to the die-head structure or by the manual rearward movement ofA the vupper end of the lever-handle 1.8.. When thetripping-sleeve 59 is moved rearwardly as described, its cam-surface 15 will act upon. the cam-surface 11. of the latch-member 12 and. force the latter inwardly. Shortly after the starting of; the inward movement of the latchmember 12 its radially-extending latching-shoulder 15a will lride-clear of the inner corner of the l'atching-abutment 14` and the sloping let-off shoulder 15bIwil1 now` ride against the inner corner 'or edge of thefsaid abutment 14and for a brief: interval of time, thus gradually retire the chasers 54 under the urge of the spring SS acting through the Chaser-operating memberV 52. As soon as the outer end of the let-off shoulder 15b has clearedthe inner edge of the latchingabutment 14,*the latch-carrying ksleeve and hence ther Chaser-operating plunger 52 will be moved quickly to; the'lrearA to thusv effect the complete retirement of the chasers 54 so that the die-head structure andthe now-threaded Vwork may be axially separated preparatory to another thread- -ing operation.

The 1er-off shomder 15b of the structure ofl without the intervention of the said let-oifshoulder 15b. l Y

The invention may be carried out invother specic ways than those herein set forthV without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning andequvalency range of the appended claims are intended to be embraced therein.

I claim:

1. An automatic-releasing thread-cutting tool, comprising: a body-unit having a latching-abutment; a plurality of substantially-radially retirable and advanceable thread-cutting chasers carried by the said body-unit; spring-means urging the said chasers into their retired or inoperative positions; a latch-releasing member; and a latch-member movable into releasing position by the said latch-releasing member and releasably holding the said chasers in their advanced or thread-cutting positions, the said latch-member being provided with a latching-abutment 'positioned to engage with the latching-abutment of theY saidbody-unit; one of the aforesaid latching-abutinents comprising a latching-shoulder and a letofi shoulder intersecting the said latching-shoulder and inclined with respect to the plane thereof at a non-camming angle of substantially less than 45, the said latching-shoulder being positioned to fixedly restrain the said chasers in their advanced or thread-cutting positions during the normal thread-cutting operation of the tool and the said let-off shoulder being positioned and inclined to cause the progressive retirement of the said chasers at the termination of the normal thread-cutting operation to substantially erase longitudinal shoulders left upon`the work by the said chasers'.

2. An automatic-releasing thread-'cutting tool, comprising: a body-unit having latching-abutment curvedlengthwise of itself; a plurality of substantially-radially retirable and advanceable thread-cutting chasers-carried by the said bodyunit; spring-means urging the said chasers into their retired or inoperative positions; a latchreleasing member; and a latch-member curved lengthwise of itself and movable into releasing position by the said latch-releasing member and releasably holding the said chasers in their advanced or thread-cutting positions, the said latch-member being provided with a latchingabutment curved lengthwise of itself and positioned to engage with the latching-abutment of the said body-unit; one of the aforesaid latchingpositions during the normal thread-cutting op-A eration of the tool and the said let-off shoulder being positioned and inclined to cause the pro? gressive retirement of theV said Vchasers at the termination of the normal thread-cutting operation to substantially erase longitudinal shoulders leftV upon the work by the said chasers.

3. An automatic-releasing thread-cutting tool,

comprising: a body-'unit having a latching-abutment; a plurality of substantially-radially retirjable and advanceable thread-cutting chasers carhold the said chasers in their advanced or' thread-cutting positions, and ,a let-off shoulder intersecting the said latching-shoulder at a noncamming angle of substantially less than 45 with respect to the plane thereof and operatively engaging the latching-abutment of the said bodyunit after the said latching-shoulder has been moved out of operative engagement with the same to subsequently cause the progressive retirement of the said chasers to substantially erase longitudinal shoulders left upon the Work by the said chasers.

4. An automatic-releasing thread-cutting tool, comprising: a body-unit having a latching-abutment curved lengthwise of itself; a plurality of substantially-radially retirable and advanceable thread-cutting chasers carried by the said bodyunit; spring-means urging the said chasers into their retired or inoperative positions; a latchreleasing member; and a latch-member curved lengthwise of itself and releasable by the said latch-releasing member and releasably holding the said chasers in their advanced or threadcutting positions, the said latch-member being provided with a latching-abutment curved lengthwise of itself and'comprising a latchingshoulder curved lengthwise of Yitself and arranged to engage with the latching-abutment of the said body-unit to xedly but releasably hold the said chasers in their advanced or thread-cutting positions, and a let-off shoulder curved lengthwise of itself and intersecting the said latching-shoulder at a non-camming angle of substantially less than 45 with respect to the plane thereof and operativelyV engaging the latching-abutment of thesaid body-unit after the said latching-shoulder has been moved out of operative engagement with the same to subsequently cause the progressive retirement of the said chasers to substantially erase longitudinal shoulders left upon the work by the said chasers.

5. A self-opening die-head, comprising: a bodyunit having a latching-abutment; a plurality of substantially-radially retirable and advanceable thread-cutting chasers carried by the said bodyunit; spring-means urging the said chasers outwardly into-their inoperative positions; a latchreleasing member; and a latch-member movable into its releasing position by the said latch-releasing member and releasably holding the said chasers in their inwardly-projected thread-cutting positions, the said latch-member being provided with a latching-abutment positioned to engage with the latching-abutment of the said bodyunit; one of the aforesaid latching-abutments comprising a latching-shoulder and a let-off shoulder intersecting the said latching-shoulder and inclined with respect to the plane thereof at a non-camming angle of substantially less than 45, thek said latching-shoulder being positioned to fiXedly restrain the said chasers in their inwardly-projected thread-cutting positions during the normal thread-cutting operation of the diehead and the said let-off shoulder being positioned and inclined to cause the progressive retirement of the said chasers at the termination of the normal thread-cutting operation to substantially erase longitudinal shoulders left upon the work by the said chasers.

6. A self-opening die-head, comprising: a bodyunit having a latching-abutment curved lengthwise of itself; a plurality of substantially-radially retirable and advanceable thread-cutting chasers Ycarried by the said body-unit; spring-means urging the said chasers outwardly into their inoperative positions; a latch-releasing member; and a latch-member curved lengthwise of itself and movable into its releasing position by the said latch-releasing member and releasably holding the said chasers in their inwardly-projected thread-cutting positions-the said latch-member being provided with a latching-abutment curved lengthwise of itself and positioned to engage with the hatching-abutment of the said body-unit; one of the aforesaid latching-abutments comprising a latching-shoulder curved lengthwise of itself and a let-off shoulder curved lengthwise of itself and intersecting the said latching-shoulder and inclined with respect to the plane thereof at a non-camming angle of substantially less than 45, the said latching-shoulder being positioned to xedly restrain the said chasers in their inwardly-projected thread-cutting positions during the normal thread-cutting operation of the diehead and the said let-off shoulder being positioned and inclined to cause the progressive retirement of the said chasers at the termination of the normal thread-cutting operation to substantially erase longitudinal shoulders left upon the work by the said chasers.

7. A collapsing tap, comprising: a body-unit having a latching-abutment; a plurality of substantially-radially retirable and advanceable thread-cutting chasers carried by the said bodyunit; spring-means urging the said chasers radially inwardly into their retired positions; a latch-releasing member; and a latch-member releasable by the said latch-releasing member and releasably holding the said chasers in their outwardly-projected thread-cutting positions, the

erative engagement with the same to subsequently y cause the progressive retirement of the said chasers to substantially erase longitudinal shoulders left upon the work by the said chasers.

8. A collapsing tap, comprising: a body-unit having a latching-abutment curved lengthwise of itself; a plurality of substantially-radially retirable and advanceable thread-cutting chasers carried by the said body-unit; spring-means urging the said chasers radially vinwardly into their retired positions; a latch-releasing member; and a latch-member curved lengthwise of itself and releasable by the said latch-releasing member and releasably holding the said chasers in their outwardly-projected thread-cutting positions, the said latch-member being provided with a latching-abutment curved lengthwise of itself and comprising a latching-shoulder curved lengthwise ofl itself and arranged to engage with the latching-abutment of the said body-unit to fxedly but releasably hold the said chasers in their advanced or thread-cutting positions, and a let-0E shoulder curved lengthwise of itself and intersecting the said latching-shoulder at a non-cammlng angie of substantially less than 45 with respect to the plane thereof and operatively engaging the latching-abutment of the said body-unit y after lthe said latching-shoulder has been moved out of operative engagement with the same to subsequent cause the progressive retirement of. 

